Walton is out of the lineup for Sunday's game against the Red Sox.
The left-handed-hitting Walton is on the bench for the fourth straight game, with the Athletics having faced lefty starters in each of those contests. Southpaw Erik Miller is likely to work only an inning or two as the Red Sox's opening pitcher Sunday, so Walton could be summoned from the bench as a mid-game replacement if a righty takes over for Boston.